Relative contribution of compositional parameters to the primary and secondary oxidation of canola oil

Overall quality changes and deterioration mechanism of fragrant rapeseed oils during 6-Month storage

The strong-fragrant rapeseed oil (SFRO) is a popular rapeseed oil in China with a low refining degree only degumming with hot water, which remarkably affects its storage stability. The present study compared the overall changes of physical/chemical/nutrient quality of FROs at various temperatures, light wavelengths and headspace volumes. Results showed that red light (680 nm) had a most significant adverse effect on the overall quality of SFRO with the higher correlation coefficients to PV and TOTOX of 0.71 and 0.70, and lower correlation coefficients to chlorophyll and tocopherol of -0.95 and -0.53, respectively. Further studies revealed that red light accelerated the oxidation of fragrant rapeseed oils by degrading chlorophyll to initiate the photo-oxidation process and synthesize high amount of secondary oxidation products including aliphatic and aromatic oxidized compounds from linolenic acid. These findings provided a reference to control the deterioration of FROs by preventing the transmittance of red light.

Value-added processing of seeds from tomato sauce industry and comparison of extraction solvents on the chemical properties

BACKGROUND

Tomato seed oil (TSO) was obtained using a combined method of pre-keeping in solvent and Soxhlet extraction. A considerable oil yield could not be obtained using samples without drying or grinding, with dried or non-dried seeds, which were not kept in solvent (<2%). For this purpose, oil yield, physicochemical properties, oxidation values, spectrophotometric indices and fatty acid composition of the samples extracted with acetone, ethyl acetate, chloroform and petroleum ether were determined.

RESULTS

Oils obtained by the extraction of petroleum ether (20.36 meq g O₂ kg^-1 ) and ethyl acetate (11.16 meq g O₂ kg^-1 ) were found to have very high peroxide values. Besides, a high-quality edible oil should have an anisidine value (p-AnV) of less than 10. Samples extracted with chloroform alone had a p-AnV of 8.86, while slightly higher values were found for other samples (P < 0.05). Chloroform (20.50) and acetone (23.06) both gave the best results and met the expected value, with total oxidation value below 30. Finally, the highest levels of primary fatty acids observed were linoleic acid (32.77-41.95%), palmitic acid (23.75-32.27%), oleic acid (16.17-24.52%), and stearic acid (7.76-12.82%).

CONCLUSION

This process is applicable to recycling tomato sauce waste and essential oil. The research proved that the seed-drying process and pre-keeping in solvent have an important effect on oil yield, quality and fatty acid composition. © 2023 Society of Chemical Industry.

Comparison and analysis characteristics of flax, perilla and basil seed oils cultivated in Iran

The oil yield, fatty acid (FA) composition, physicochemical, quality characteristics and thermal properties were studied in flax, perilla, and basil seed oils cultivated in Iran. Also the similarities and differences among these seed oils were investigated using principal component analysis (PCA). The results indicated that perilla seed oil contained the highest lipid content followed by flax and basil seed oils. The n-6/n-3 FA ratios of these oils had a range of 0.190-0.320, which was notably lower than those of most vegetable oils. Trilinolenin as the predominant triacylglycerol in the studied flax, perilla, and basil seed oils was found at 21.3, 32.0, and 27.5%, respectively. The bioactive compounds, namely tocols, phytosterols, and total phenolics, present in basil and perilla oils were higher than those of flax seed oil. The results of differential scanning calorimeter indicated that the thermal properties of these seed oils were varied, with lower melting and crystallization peak temperature for perilla and basil seed oils. The results of PCA showed that these seed oils could be distinguished using some components however, C14:0, C16:0, C18:3, UFA and ECN 42 could not be used to discriminate among these seed oils. The results were suggestive of the proper nutritional qualities of the studied oils and their possibly being the potential sources of FAs for enriching the diets with α-linolenic acid and other functional compounds.

Formation of potentially toxic carbonyls during oxidation of triolein in the presence of alimentary antioxidants

ABSTRACT

A relation between oil uptake and cancer as well as induction of hepatic inflammation was shown earlier. It is discussed that the main oil oxidation products-hydroperoxides and carbonyls-might be the reason for the mentioned diseases. In this manuscript quantitative determination of aldehydes which are formed during oxidation of triolein-as a model substance-using the Rancimat 679 is described. The oxidation of 11 g of triolein is carried out at 120 °C sparging air with a flow of 20 dm3/h for 10 h. A series of aliphatic aldehydes starting from hexanal to decanal as well as decenal was identified by LC-MS/MS and quantified as DNPH derivatives. In addition, the total amount of carbonyls was determined. Based on the calibration with hexanal, all other dominant substances were in the similar concentration range with maximum concentrations of 1.6 µmol/cm3 of hexanal, 2.3 µmol/cm3 of heptanal, 2.5 µmol/cm3 of octanal, 3.2 µmol/cm3 of nonanal, 4.0 µmol/cm3 of decanal after 6 h. The total amount of carbonyls reached a maximum after 6 h being 27 µmol/cm3 for triolein without antioxidant. The results of this investigation will be a basis for further toxicological studies on oxidized oils.

GRAPHICAL ABSTRACT

Synergetic Use of Principal Component Analysis Applied to Normed Physicochemical Measurements and GC × GC-MS to Reveal the Stabilization Effect of Selected Essential Oils on Heated Rapeseed Oil

Lipid oxidation leads to the formation of volatile compounds and very often to off-flavors. In the case of the heating of rapeseed oil, unpleasant odors, characterized as a fishy odor, are emitted. In this study, 2 different essential oils (coriander and nutmeg essential oils) were added to refined rapeseed oil as odor masking agents. The aim of this work was to determine a potential antioxidant effect of these essential oils on the thermal stability of rapeseed oil subject to heating cycles between room temperature and 180 °C. For this purpose, normed determinations of different parameters (peroxide value, anisidine value, and the content of total polar compounds, free fatty acids and tocopherols) were carried out to examine the differences between pure and degraded oil. No significant difference was observed between pure rapeseed oil and rapeseed oil with essential oils for each parameter separately. However, a stabilizing effect of the essential oils, with a higher effect for the nutmeg essential oil was highlighted by principal component analysis applied on physicochemical dataset. Moreover, the analysis of the volatile compounds performed by GC × GC showed a substantial loss of the volatile compounds of the essential oils from the first heating cycle.

Use of Iranian Milkweed Seed Oil to Increase Oxidative Stability of Olive Cultivar Roghani Oil

This study aimed to evaluate fatty acid composition and physicochemical properties of Iranian milkweed seed oil (IMSO) and olive cultivar Roghani oil (OCRO). The extraction yield and unsaturated fatty acids content of IMSO were 21.9 % (dry basis) and 65 %, respectively. The monounsaturated fatty acids/polyunsaturated fatty acids ratio, calculated oxidizability, peroxide value, unsaponifiable matter, total tocopherol content, total phenolic content, total sterol, wax content, carbonyl value, conjugated diene value and oxidative stability index of IMSO and OCRO were measured. The results indicated that oxidation stability (OS) of IMSO (6.46 h) was significantly higher than OS of OCRO (5.53 h). In addition, application of IMSO to OCRO resulted in higher OS that was the greatest after 10 % addition of IMSO.

Effect of rosemary (Rosmarinus officinalis) extracts on the oxidative stability and sensory acceptability of soybean oil

BACKGROUND

Plant extracts have been used as an alternative to the use of synthetic antioxidants in order to preserve oils from oxidative degradation. Additionally, these extracts add special flavors and aromas to the food. Thus, the objective of this study was to evaluate the effect of hydroethanolic extracts of fresh and freeze-dried rosemary in the oxidative stability of soybean oil under accelerated storage in an oven.

RESULTS

The application of the extracts in the oil showed that that freeze-dried extract was better in reducing the formation of oxidation products, showing 8.6 meq kg(-1) of peroxides after 20 days of storage. On the other hand, the mixture of the natural extract with t-butylhydroquinone conferred better oxidative stability index until the 20th day, 9.7 h. Both extracts prevented the loss of tocopherol, not differing between each other (P > 0.05), and present approximately 505 mg kg(-1) of residual tocopherols. The sensory evaluation revealed that consumers accepted equally the oils added and not added of the rosemary extracts.

CONCLUSION

The extracts are therefore potential sources of natural antioxidants and they would be well accepted by consumers if applied by the food industry to replace synthetic antioxidants.

A simplified FTIR chemometric method for simultaneous determination of four oxidation parameters of frying canola oil

Transmission Fourier transform infrared (FTIR) spectroscopic method using 100 μm KCl cell was applied for the determination of total polar compounds (TPC), carbonyl value (CV), conjugated diene (CD) and conjugated triene (CT) in canola oil (CLO) during potato chips frying at 180 °C. The calibration models were developed for TPC, CV, CD and CT using partial least square (PLS) chemometric technique. Excellent regression coefficients (R(2)) and root mean square error of prediction values for TPC, CV, CD and CT were found to be 0.999, 0.992, 0.998 and 0.999 and 0.809, 0.690, 1.26 and 0.735, respectively. The developed calibration models were applied on samples of canola oil drawn during potato chips frying process. A linear relationship was obtained between CD and TPC with a good correlation of coefficient (R(2)=0.9816). Results of the study clearly indicated that transmission FTIR-PLS method could be used for quick and precise evaluation of oxidative changes during the frying process without using any organic solvent.

Independent components analysis coupled with 3D-front-face fluorescence spectroscopy to study the interaction between plastic food packaging and olive oil

Olive oil is one of the most valued sources of fats in the Mediterranean diet. Its storage was generally done using glass or metallic packaging materials. Nowadays, plastic packaging has gained worldwide spread for the storage of olive oil. However, plastics are not inert and interaction phenomena may occur between packaging materials and olive oil. In this study, extra virgin olive oil samples were submitted to accelerated interaction conditions, in contact with polypropylene (PP) and polylactide (PLA) plastic packaging materials. 3D-front-face fluorescence spectroscopy, being a simple, fast and non destructive analytical technique, was used to study this interaction. Independent components analysis (ICA) was used to analyze raw 3D-front-face fluorescence spectra of olive oil. ICA was able to highlight a probable effect of a migration of substances with antioxidant activity. The signals extracted by ICA corresponded to natural olive oil fluorophores (tocopherols and polyphenols) as well as newly formed ones which were tentatively identified as fluorescent oxidation products. Based on the extracted fluorescent signals, olive oil in contact with plastics had slower aging rates in comparison with reference oils. Peroxide and free acidity values validated the results obtained by ICA, related to olive oil oxidation rates. Sorbed olive oil in plastic was also quantified given that this sorption could induce a swelling of the polymer thus promoting migration.

In vitro kinetics of soybean lipoxygenase with combinatorial fatty substrates and its functional significance in off flavour development

Lipoxygenase (Lox) mediated oxidation of polyunsaturated fatty acids (PUFA) in mature soya seeds results in objectionable flavour. In the present study, Lox isozymes were purified to near homogeneity (107-fold). Lox-2 and 3 displayed remarkable kinetic preference (1.7 and 1.5-fold, respectively) for low PUFA ratios (LA/LeA) (PRs) among the selected PUFA combinations. Lox-1 displayed no specific preference. Pure Lox-1 displayed unbiased response towards substrates with marginal preference (1.2-fold) for linoleic acid at its optimum pH. Volatile compounds profiling showed a direct relationship between PRs and hexanal to trans-2-hexenal (1.47, 2.24 and 18.90 for 2, 7 and 15 PRs, respectively) ratio. The off-flavour determining parameters like TBA value, carbonyl value and lipid hydroperoxides (LHPODs) exhibited significant negative correlation (0.76, 0.74, 0.72; p<0.0001) in selected soya genotypes displaying varied PRs and significant positive correlation (0.89, 0.81. 0.89; p<0.0001) with ratio of PI (polyene index) to PRs - suggesting the plausible significance of PUFA ratios in biological lipid peroxidation.

Rapid measuring and modelling flavour quality changes of oxidised chicken fat by electronic nose profiles through the partial least squares regression analysis

The objective of this study was to investigate whether an electronic nose, comprising 18 metal oxide semiconductor gas sensors, could be used for measuring and modelling flavour quality changes of refined chicken fat during controlled oxidation. Partial least squares regression (PLSR) was applied to determine the predictive relationships between the chemical parameters, GC-MS data, free fatty acid profiles and electronic nose responses for controlled oxidation of refined chicken fat. The results showed that peroxide value (PV) and acid value (AV) were significantly well predicted by the electronic nose responses, whereas p-anisidine value (p-AV) was found to be fairly well predicted especially for deeply oxidised chicken fat. Thus, this study gave evidence of the electronic nose system to be a promising device for future at- or on-line implementation in oxidation control of chicken fat for producing meat flavourings.